The trend toward this effect persisted even after researchers controlled for age and body mass index, and was not seen in women who were more active.

The results showed a “compounded adverse metabolic effect of prolonged sitting time in women with PCOS who do not achieve exercise goals,” according to Eleni Greenwood, MD, and her colleagues at the University of California, San Francisco, department of obstetrics, gynecology, and reproductive sciences.

PCOS is known to be associated with many adverse metabolic outcomes, including impaired glucose tolerance, type 2 diabetes, obesity, and cardiovascular disease.

“In PCOS, insulin resistance is tissue specific and occurs in the skeletal muscle,” said Dr. Greenwood, a fellow in the reproductive endocrinology and infertility program at the University of California, San Francisco. Diet and exercise are primary interventions to help with these sequelae. In the general population, prolonged time spent being sedentary is associated with type 2 diabetes, cardiovascular disease, and even some cancers.

Because “the adverse effects of sitting are not reversed through exercise,” as Dr. Greenwood and her colleagues pointed out, the study sought to ascertain whether worse metabolic parameters would be seen in women with PCOS who had had more sedentary time, and whether the association would be independent of exercise status.

Accordingly, the investigators conducted a cross-sectional study of 324 women who met Rotterdam criteria for PCOS. The results were presented during a poster session at the annual meeting of the Endocrine Society.

Patients took the International Physical Activity Questionnaire, and responses were used to determine activity levels and amounts of sedentary times. Other measurements taken at the interdisciplinary clinic where the patients were seen included anthropometric measurements, as well as the results of serum lipid levels, fasting glucose and insulin levels, and the results of a 75-g, 2-hour oral glucose tolerance test (OGTT).

In their analysis, the investigators calculated homeostasis model assessment of insulin resistance (HOMA-IR), and used multivariable analysis to find correlations and eliminate potentially confounding variables. In a further attempt to eliminate confounders, Dr. Greenwood and her colleagues asked patients to stop hormonal contraceptive methods and insulin sensitizing medications 30 days before beginning the study.

The investigators looked at the women’s exercise status, meaning whether they had achieved the level of activity recommended by the U.S. Department of Health & Human Services. However, they also asked the women to report how sedentary they were, measured by the number of hours spent sitting in a day.

It would theoretically be possible for an individual to be very “active,” exercising vigorously for 2 hours each day, but also very “sedentary,” sitting for much of the rest of her waking hours.

Overall, two-thirds of the women (217, 67%) met the activity goals outlined by the HHS. That consisted of exercising enough to achieve 600 metabolic equivalents per week. If the women sat for more than 6 hours a day, they were judged to be sedentary. Of the inactive women, 35% (37) sat for 6 or fewer hours per day, compared with 44% (94) of the active women.

Though the results did not reach statistical significance, HOMA-IR and post-OGTT glucose levels tended to be lower among those who sat less (1.93 vs. 2.73, P = .10; 99 mg/dL vs. 107 mg/dL, P = .09).

Looking at just the inactive group, less sitting time was associated with significantly lower post-OGTT glucose levels (99.1 mg/dL vs. 117.6 mg/dL, P = .03). This difference was not seen among the group of women judged to be active.

“Our results indicate a compounded adverse metabolic effect of prolonged sitting time in women with PCOS who do not achieve exercise goals,” wrote Dr. Greenwood and her collaborators.

Because PCOS pathophysiology can be “disrupted” by an improvement in insulin sensitivity and overall metabolic health, “women with PCOS should be counseled regarding strategies for reducing sedentary time, in addition to improving exercise and diet, as a means of improving metabolic health,” they said.

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